• CakePHP 2.0.X
• A PayPal Website Payments Pro account
• A API username, password and signature (From PayPal -> Profile -> API Settings -> Signature)
• A valid SSL certificate

This component can handle two type of PayPal transaction, Express Checkout and Direct Payment.

https://cms.paypal.com/us/cgi-bin/?cmd=_render-content&content_ID=developer/e_howto_api_WPGettingStarted

First, set some basic information about the transaction you want to perform, amount, currency etc. and call Paypal::expressCheckout().

The user is redirected to PayPal where they log in, they are then redirected back to your site (to the return URL).

You can then use Paypal::getExpressCheckoutDetails() to fetch basic customer information, their billing address etc.

If they are happy and want to proceed with purchase, call Paypal::doExpressCheckoutPayment() which then completes the payment.

https://cms.paypal.com/us/cgi-bin/?cmd=_render-content&content_ID=developer/e_howto_api_WPDirectPayment

The customer enters their billing information on your website (SSL required) and you use this to call Paypal::doDirectPayment() which will attempt to bill their card.

Do not store credit card numbers, CVV numbers etc. in your database, sessions, cookies.